1. Field
Exemplary embodiments of the present invention relate to a method for fabricating a semiconductor device and more particularly, to a method for forming void-free polysilicon and a method for fabricating a semiconductor device using the same.
2. Description of the Related Art
When a contact plug, such as a bit line contact plug or storage node contact plug, is formed, polysilicon may be used.
However, when a contact hole having a high aspect ratio is gap-filled with polysilicon, slits occur in the polysilicon. The slits occur when the surfaces of polysilicon which is grown while depositing from the bottom surface of the contact hole meet each other. The slits are hold together in a direction to minimize the surface areas of the slits and then develop into a void during a subsequent thermal process. Therefore, as a semiconductor device is highly integrated, the size of a void existing in a contact plug increases.
Such a void randomly exists inside the contact plug. However, as a subsequent heat process is performed, the void may be moved to a top or bottom interface or a side interface, thereby increasing interface resistance of the contact plug. Furthermore, when a void exists in polysilicon, the void may increase bulk resistance, thereby causing a resistive fail.